Mineralogy of the sand fraction of the following soil Series is being studied: Osomo, Arrayan, Santa Barbara, Mirador and Nueva Braunau; only the top horizons are taken into consideration.
Permanent glass slides were mounted with canada balsam. Observation were carried out with polarized light.
In these soils feldspars and volcanic glasses are domihant. The latter are mixed and of acid and basic nature. Mafic minerals are not abundant.
This is a preliminary study and more detailed descriptions are recommended.